Medical imaging system and fluid-driven injector

ABSTRACT

Some injectors of the invention may include a fluid drive responsive to pressure of a working fluid (e.g., liquid, pneumatic, or both) to impart a sequence of forces to drive a delivery device (e.g., a syringe) to deliver a medical fluid (e.g., a contrast agent, a radiopharmaceutical, a drug, or a combination thereof). Some injectors may include a multimedia tube configured to pass a working fluid (e.g., air) and a light signal (e.g., infrared). Some injectors may include a peristaltic drive responsive to pressure of a working fluid.

RELATED APPLICATIONS

This application is a U.S. National Stage of PCT/US2008/0072978, filedon 13 Aug. 2008, which claims priority to U.S. provisional applicationSer. No. 60/965,364 filed on 20 Aug. 2007 entitled FLUID DRIVEN MEDICALINJECTORS. Priority is claimed to each patent application set forth inthis Related Applications section.

FIELD OF THE INVENTION

The present invention relates generally to medical fluid injectors and,more particularly, to contrast media injectors used in medical imagingprocedures.

BACKGROUND

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present invention,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentinvention. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

In various medical modalities, a powered injector is used to inject thepatient with a medical fluid, such as a drug, a contrast agent, aradiopharmaceutical, or a combination thereof. A typical poweredinjector includes a motor that drives a ram, which in turn drives aplunger of a syringe. Unfortunately, the motor and other electronics inthe powerhead typically emit radiofrequency (RF) radiation that candetrimentally affect operation of medical equipment, such as a magneticresonance imaging (MRI) system. In addition, the medical equipment, suchas the MRI system, typically emits RF radiation that can detrimentallyaffect operation of the powerhead. Although existing powered injectorsfor MRI applications typically include radiation shielding, thedetrimental affects of RF radiation can still hinder proper functioningof both the powerhead and the medical equipment.

In addition to the problems with RF radiation, existing poweredinjectors are generally too large, awkward, or inconvenient to placewith the patient inside the magnet bore of the MRI system. Instead, thepowerhead is placed outside the magnet bore, and a long run of tubing isused to connect the syringe tip with the injection site. A normal lengthof tubing may range from about 60 to 90 inches, and may contain as muchas 4 to 5 milliliters of fluid. Unfortunately, this volume of fluidremains within the tubing after injecting the fluid from within thesyringe, because movement of the syringe plunger cannot inject it intothe patient. A typical MRI protocol may prescribe 20 milliliters ofcontrast agent, leaving about 4 to 5 milliliters of contrast agent (25percent) within the tubing after the injection. A shortage of 25 percentof the prescribed contrast agent may hinder the image enhancement. MRIcontrast agent, such as gadolinium, is very expensive and may beconsidered cost prohibitive to waste 4 to 5 milliliters of contrastagent per procedure. Existing MRI injectors typically have a secondsyringe that is filled with a flushing solution, such as saline. At thecompletion of the contrast injection, the injector chases the contrastagent down the tubing with the saline. This method ensures that theentire volume of contrast agent has been injected into the patient.Thus, only 4 to 5 milliliters of saline has been wasted, which issignificantly less expensive than the MRI contrast agent. Unfortunately,the injected volume of saline does not offer any imaging benefits to thepatient, while also adding complication, costs, and time to theprocedure.

SUMMARY

Certain exemplary aspects of the invention are set forth below. Itshould be understood that these aspects are presented merely to providethe reader with a brief summary of certain forms the invention mighttake and that these aspects are not intended to limit the scope of theinvention. Indeed, the invention may encompass a variety of aspects thatmay not be set forth below.

A first aspect of the present invention is directed to a medical fluidinjector that includes a fluid drive responsive to pressure of a workingfluid (e.g., liquid, pneumatic, or both) to impart a sequence of forcesto drive a delivery device (e.g., a syringe) to deliver a medical fluid(e.g., a contrast agent, saline, a radiopharmaceutical, a drug, or acombination thereof). The sequence of forces may be defined as a seriesof separate and discrete forces, which are generated and/or occur oneafter another, rather than a single constant force. In other words, thesequence of forces may be defined as a pulse-like sequence or a rhythmicreoccurrence of the forces. The sequence of forces may includeperistalsis, which may be described as a rhythmic contraction of a fluidpassage to propel a working fluid through the fluid passage. Forexample, peristalsis may include contraction of the fluid passage in asequence at one axial position after another along the length of thefluid passage. The sequence of forces also may include pulsatile forces,oscillating forces, stepwise forces, or a combination thereof. Forexample, the sequence of forces may progressively force a gear to rotateby engaging one tooth after another in discrete steps, e.g., contact afirst tooth, push it forward, step to a second tooth, push it forward,and so on. Each force in the sequence may be equal or different. Also,each force in the sequence may be separated in time and/or spatialposition.

A second aspect of the invention is directed to a medical fluid injectorthat includes a multi-fluid drive having a pneumatic drive section(e.g., a piston-cylinder arrangement) coupled to a liquid controlsection (e.g., a piston-cylinder arrangement). The pneumatic drivesection is responsive to pressure of a working pneumatic medium (e.g.,air) to induce movement. The liquid control section may include aworking liquid (e.g., oil, water, alcohol, etc.) responsive to themovement to control a rate of the movement. This movement may be used todrive a delivery device (e.g., to provide a discharge of medical fluidfrom the delivery device, for instance when in the form of a syringe).

Yet a third aspect of the invention is directed to a medical fluidinjector that includes a multimedia tube that is configured to pass aworking fluid (e.g., air) and a light signal (e.g., infrared). Themultimedia tube may be capable of sending data, control signals, motiveforces, or a combination thereof, based on different types of media(e.g., air, infrared, etc.). Thus, multiple types of media pass througha single tube (e.g., the multimedia tube), thereby reducing the amountof tubing used in an injection procedure. The working fluid may be usedby a fluid drive to drive a delivery device (e.g., to provide adischarge of medical fluid from the delivery device, for instance whenin the form of a syringe), while the light signal may be used to controla valve, that in turn controls or otherwise has an effect on a flow ofthe working fluid.

Still a fourth aspect of the invention is directed to a medical fluidinjector that includes a peristaltic chive (e.g., sequential movementsto drive a fluid) responsive to pressure of a working fluid (e.g.,pneumatic, liquid, or both). For example, the peristaltic drive mayinclude a series of mechanisms (e.g., pistons), which sequentiallysqueeze a tube to create a rhythmic contraction to propel a medicalfluid. The pistons may be moved by the working fluid.

A fifth aspect of the invention is directed to a method of operation fora medical fluid injector. The method includes responding to pressure ofa working fluid (e.g., pneumatic, liquid, or both) to impart a sequenceof forces to drive a delivery device (e.g., syringe, needle, or both) todeliver a medical fluid. For example, a series of control signals or airpulses may cause a series of pistons to apply forces to a fluid passageone after another, thereby creating a rhythmic contraction of the fluidpassage to propel the medical fluid along the fluid passage.

Still yet a sixth aspect of the invention is directed to a method ofimaging a patient. In this method, a powerhead of a contrast mediainjector is removably mounted on a patient (e.g., via one or more strapsdisposed about a limb of the patient). Contrast media is injected intothe patient while the powerhead is removably mounted on the patient.Further, the patient is also imaged (e.g., via a magnetic resonanceimaging system) while the powerhead is removably mounted on the patient.

Numerous refinements exist of the features noted above in relation tothe various aspects of the present invention. Further features may alsobe incorporated in these various aspects as well. These refinements andadditional features may exist individually or in any combination. Forinstance, various features discussed below in relation to one or more ofthe illustrated embodiments may be incorporated into any of theabove-described aspects of the present invention alone or in anycombination. Again, the brief summary presented above is intended onlyto familiarize the reader with certain aspects and contexts of thepresent invention without limitation to the claimed subject matter.

BRIEF DESCRIPTION OF THE FIGURES

Various features, aspects, and advantages of the present invention willbecome better understood when the following detailed description is readwith reference to the accompanying figures in which like charactersrepresent like parts throughout the figures, wherein:

FIG. 1 is a diagram of a fluid driven injector disposed in an imagingbore of an imaging system;

FIG. 2 is a diagram of a fluid driven injector having pneumatic andliquid drive sections;

FIG. 3 is a diagram of a fluid driven peristaltic injector;

FIG. 4 is a diagram of an injector having a fluid driven ratchet andgear assembly;

FIG. 5 is a partial view of the ratchet and gear assembly of FIG. 4;

FIG. 6 is a diagram of a fluid driven injector having a docking rechargestation;

FIG. 7 is a diagram of an embodiment of the injector and station of FIG.6;

FIGS. 8 and 9 are diagrams of alternative fluid driven injectors havingpneumatic and liquid drive sections; and

FIG. 10 is a diagram of a fluid driven injector coupled to a dockingrecharge station via a multimedia tube.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments of the present invention will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions must be madeto achieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

When introducing elements of various embodiments of the presentinvention, the articles “a”, “an”, “the”, and “said” are intended tomean that there are one or more of the elements. The terms “comprising”,“including”, and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.Moreover, the use of “top”, “bottom”, “above”, “below” and variations ofthese terms is made for convenience, but does not require any particularorientation of the components. As used herein, the term “coupled” refersto the condition of being directly or indirectly connected or incontact. Additionally, the phrase “in fluid communication” or “fluidlycoupled” indicates that fluid and/or fluid pressure may be transmittedfrom one object to another.

FIG. 1 is a diagram of an exemplary imaging suite 10 having a fluiddriven injector 12 disposed within an imaging bore 14 of an imagingsystem 16. The illustrated injector 12 includes a fluid drive 18, afeedback sensor 20, and a medical fluid delivery device 22. The deliverydevice 22 receives and/or stores a medical fluid 24 for delivery to apatient positioned within the imaging bore 14 during an imagingprocedure. The imaging suite 10 also includes a control 26, a fluid pump28, and a working fluid 30. The imaging system 16 further includesimaging circuitry 32 coupled to the bore 14, and an imaging controlstation 34 coupled to the imaging circuitry 32 and the control 26.

In the illustrated embodiment, the imaging suite 10 may operate as aclosed loop control system. For example, the control 26 may output acontrol signal 36 to the fluid pump 28, thereby triggering the pump 28to receive and transfer a working fluid 30 to the fluid drive 18 asindicated by arrows 38 and 40, respectively. Thus, arrow 36 mayrepresent an electronic, optical, or other appropriate control line;whereas arrows 38 and 40 may represent fluid conduits. For example, theworking fluid 30 may include a pneumatic substance, a liquid substance,or a combination thereof. The pneumatic substance may include air,nitrogen, or another suitable non-combustible gas. The liquid mayinclude water, oil, or a suitable hydraulic fluid.

In response to pressure of the working fluid 30, the fluid drive 18 mayimpart a driving force 42 onto the delivery device 22. For example, thefluid drive 18 may move a piston, a ram, a ratchet and gear assembly, aperistaltic device, or a combination thereof, thereby creating thedriving force 42 to displace the medical fluid 24 within the deliverydevice 22. In certain embodiments, the delivery device 22 may include asyringe having a plunger disposed within a barrel. Thus, the medicalfluid 24 may be stored within the syringe until the fluid drive 18imparts the driving force 42.

The feedback sensor 20 may monitor one or more parameters of the fluiddrive 18. For example, the sensor 20 may obtain data relating to asensed parameter as indicated by arrow 44. For example, the sensedparameter 44 may include a position, velocity, acceleration,temperature, pressure, or other operational characteristic of the fluiddrive 18. On some embodiments, the sensor 20 may include a potentiometer(e.g., linear or rotary) or an optical encoder. In turn, the sensor 20provides a feedback signal 46 to the control 26. Based on the signal 46,the control 26 may increase, decrease, terminate, or maintain output ofthe pump 28 via the control signal 36. As a result, the imaging suite 10has proportional, servo feedback control of the fluid driven injector12.

As illustrated in FIG. 1, the injector 12 and the bore 14 are located inthe imaging suite 10 on a first side of a wall 48, while the control 26,the pump 28, the working fluid 30, the imaging circuitry 32, and thecontrol station 34 are disposed in the imaging suite 10 on an oppositeside of the wall 48. The wall 48 may include certain shieldingmaterials, such as electromagnetic shielding materials, which maysubstantially reduce undesirable interference between the imaging bore14 and the control 26, the fluid pump 28, the circuitry 32, and thestation 34. The illustrated injector 12 may be substantially or entirelyfree of ferrous, or magnetic, or ferromagnetic materials. The injector12 may be substantially free of electronics, motors, or other devicesthat may emit or become adversely affected by RF radiation. For example,the fluid drive 18 and the delivery device 22 may be made substantiallyor entirely of plastics, ceramics, glass, or a combination thereof.

Again, the injector 12 is driven by the fluid pressure of the workingfluid 30 supplied by the pump 28. Given that the pump 28 and the control26 are disposed outside of the room on an opposite side of the wall 48,these components 26 and 28 do not interfere with the imaging bore 14,and vice versa. Instead, only the working fluid 30 may be transferredfrom one side of the wall 48 to the other, thereby driving the injector12 in a non-interfering manner with regard to the imaging system 16. Inaddition, the injector 12 has a relatively compact size and streamlinedshape, which is particularly suited for mounting on or near a patientwithin the imaging bore 14. As a result, the delivery device 22 may bedisposed in close proximity to the patient, thereby substantiallyreducing or eliminating long runs of tubing from the delivery device 22to the patient. Advantageously, this close proximity may reduce oreliminate the desire for a flushing solution, such as saline.

The illustrated imaging system 16 may be a magnetic resonance imaging(MRI) system or another medical imaging modality. In operation, thecircuitry 32 receives and processes data to generate an image of thepatient within the imaging bore 14. The control station 34 enables auser to control operation of the imaging circuitry 32, the control 26,or a combination thereof. For example, the user may initiate aninjection protocol via the imaging control station 34 as illustrated byarrow 50. As another example, the control station 34 may initiate animaging protocol via the imaging circuitry 32.

FIG. 2 is a diagram of another embodiment of the imaging suite 10,wherein the injector 12 has a multi-fluid drive 60. Specifically, themulti-fluid drive 60 may include a pneumatic drive section 62 coupled toa liquid drive section 64. The injector 12 also includes a syringe 66driven by the multi-fluid drive 60. Furthermore, the system 10 includesfeedback sensors 68, 70, and 72 coupled to a control 74, which is inturn coupled to a pneumatic pump 76. In operation, the control 74provides a control signal 78 to the pump 76, thereby triggering the pump76 to intake and transfer a working pneumatic medium 80 to the pneumaticdrive section 62, as indicated by arrows 82 and 84, respectively. Inresponse to the pneumatic pressure from the pump 76, the pneumatic drivesection 62 provides a pneumatic driven pressure or force 86 to theliquid drive section 64, thereby causing the liquid drive section 64 toprovide a liquid driven force or pressure 88 onto the syringe 66.Specifically, the liquid drive section 64 may force a plunger 90 to movelengthwise along a barrel 92 of the syringe 66. Advantageously, theworking pneumatic medium 80 provides generally clean power to themulti-fluid drive 60, while the liquid working medium disposed in theliquid drive section 64 provides more accurate control of the movementand/or force 88 imparted to the syringe 66.

The feedback sensors 68, 70, and 72 may monitor and obtain dataregarding one or more sensed parameters 94, 96, and 98 of the section62, the section 64, and the plunger 90, respectively. For example, theparameters 94, 96, and 98 may include data regarding position, velocity,acceleration, temperature, pressure, or a combination thereof, which isthen transferred to the control 74 as various feedback signals 100, 102,and 104. Thus, similar to the embodiment of FIG. 1, the imaging suite 10of FIG. 2 can operate as a closed loop control system.

FIG. 3 is a diagram of another embodiment of the imaging suite 10,wherein the injector 12 includes a peristaltic fluid drive 110configured to create a sequence of forces to cause peristaltic fluidflow. In the illustrated embodiment, the peristaltic fluid drive 110 mayinclude a cylinder block 112 having a plurality of cylinders 114, 116,118, and 120 (any appropriate number of cylinders may be utilized by theperistaltic fluid drive 110), which may be arranged generally transverseor perpendicular to a passage 122 (e.g., the cylinders 114, 116, 118,and 120 may be aligned with the passage 122). The peristaltic fluiddrive 110 includes a plurality of pistons 124, 126, 128, and 130disposed in respective cylinders 114, 116, 118, and 120 (e.g., eachcylinder includes a corresponding piston). Furthermore, a flexibleconduit 132 may extend lengthwise through the passage 122. Asillustrated, the pistons 124, 126, 128, and 130 are configured to moveupward and downward in a reciprocating manner within the respectivecylinders 114, 116, 118, and 120, such that the pistons 124, 126, 128,and 130 open and close the passage 122 in a sequential manner to createa peristaltic wave lengthwise through the passage 122. With the flexibleconduit 132 installed within the passage 122, the sequential downwardmovement (e.g., sequence of forces) of the pistons 124, 126, 128, and130 onto the flexible conduit 132 creates a rhythmic contraction of theflexible conduit 132 to propel a medical fluid 134 through theperistaltic fluid drive 110 to a medical fluid delivery device 136. Inother words, the pistons 124, 126, 128, and 130 produce a series ofseparate and discrete forces at different times and axial positionsalong the flexible conduit 132. In this manner, the pistons 124, 126,128, and 130 create peristaltic fluid flow by contracting the flexibleconduit 132 in a sequence at one axial position after another along thelength of the flexible conduit 132. In certain embodiments, the medicalfluid 134 may include a drug, a contrast agent, a radiopharmaceutical,saline, or a combination thereof. Moreover, the delivery device 136 mayinclude a hollow injection needle, a short run of tubing, or anothersuitable injection device.

The sequential movement of the pistons 124, 126, 128, and 130 may beachieved by one or more fluid conduits coupled to one or more fluidpumps disposed on an opposite side of the wall 48 from the injector 12.For example, in the illustrated embodiment, the imaging suite 10 mayinclude fluid conduits 138, 140, 142, and 144 coupled to the respectivecylinders 114, 116, 118, and 120, and a manifold 146. The manifold 146may include or couple with one or more valves 148 and one or more fluidpumps 150. For example, the imaging suite 10 may include a single fluidpump 150 and valves 148 corresponding to the number of pistons andcylinders of the fluid drive 110 (four in the illustrated embodiment).Alternatively, the imaging suite 10 may include fluid pumps 150 andvalves 148 corresponding to the number of pistons and cylinders of thefluid drive 110 (four in the illustrated embodiment).

The fluid pump(s) 150 may intake and deliver a working fluid 152 inresponse to one or more control signals 154 from a control 156. Inresponse to the control signal(s), the fluid pump(s) 150 and valves 148cooperate to supply the working fluid 152 in sequential pulses one afteranother to the respective cylinders 114, 116, 118, and 120, therebycausing the pistons 124, 126, 128, and 130 to sequentially compress theflexible conduit 132 disposed within the passage 122. Similar to theembodiments of FIGS. 1 and 2, the illustrated peristaltic fluid drive110 may be non-magnetic, non-ferrous, or a combination thereof. Thus,the fluid drive 110 does not interfere or become detrimentally impactedby RF radiation or magnetics associated with the MRI system.

FIG. 4 is a diagram of an alternative embodiment of the imaging suite10, wherein the injector 12 includes a fluid drive 160 coupled to a gearand ratchet assembly 162 to create a sequence of forces. The illustratedfluid drive 160 may include a piston 164 disposed moveably within acylinder 166, wherein the piston 164 is coupled to a rod 168. Theillustrated piston 164 divides the cylinder 166 into a first chamber 170and a second chamber 172, which are coupled to a manifold 174 viarespective first and second conduits 176 and 178. Similar to theembodiment of FIG. 3, the manifold 174 may include or couple with one ormore valves 180 and one or more fluid pumps 182, such that a workingfluid 184 can be forced to flow in a reciprocating manner to the firstand second chambers 170 and 172 via the first and second conduits 176and 178. For example, as the working fluid 184 flows from the manifold174 toward the first chamber 170, the working fluid flows from thesecond chamber 172 toward the manifold 174. Upon reversing the directionof the piston 164, the working fluid 184 flows from the manifold 174into the second chamber 172, while the working fluid 184 flows from thefirst chamber 170 toward the manifold 174. Arrows 186 and 188 illustratethis reciprocating flow within the first and second conduits 176 and178. As a result of this reciprocating flow, the piston 164 and the rod168 move in a reciprocating manner (upward and downward in the viewshown in FIG. 4) within the cylinder 166, thereby imparting areciprocating force on the gear and ratchet assembly 162.

The gear and ratchet assembly 162 may include a ram 190, a ball screw192 coupled to the ram 190, a gear 194 coupled to the ball screw 192,one or more bearings 196 coupled to the gear 194 and/or the ball screw192, and a ratchet assembly 198. The ratchet assembly 198 may beconfigured to progressively engage the gear 194 in a stepwise manner inresponse to reciprocating motion of the rod 168. The ratchet assembly198 may include a first arm 200, a second arm 202, and a third arm 204disposed between the first and second arms 200 and 202. Moreover, thethird arm 204 may rotatably couple with both the first and second arms200 and 202 at rotational joints 206 and 208. Finally, the third arm 204may couple to a bearing 210. As a result, the first arm 200 can rotateabout the rotational joint 206 as indicated by arrow 212, the second arm202 can rotate about the rotational joint 208 as indicated by arrow 214,and the third arm 204 can rotate relative to the bearing 210 asillustrated by arrow 216. Each of the first arm 200 and second arm 202may be characterized as ratchets of the ratchet assembly 198.

In response to the reciprocating motion of the rod 168, the first andsecond arms 200 and 202 may reciprocate forward and backward to stepalong and sequentially push teeth 218 of the gear 194 with a sequence offorces, thereby progressively driving the gear 194 to rotate the ballscrew 192. Again, the sequence of forces may be defined as a series ofseparate and discrete forces, which are generated and/or occur one afteranother rather than a single constant force. In the illustratedembodiment, for example, the sequence of forces applied by the first andsecond arms 200 and 202 may progressively force the gear 194 to rotateby engaging one tooth 218 after another in discrete steps, e.g., contacta first tooth 218, push it forward, step to a second tooth 218, push itforward, and so on. As the ball screw 192 rotates, the ram 190 may beforced to translate a plunger 220 disposed within a barrel 222 of asyringe 224. Specifically, the plunger 220 may include a plurality ofseals disposed about a plunger head 228, which is coupled to a driveshaft 230 leading to the ram 190.

The imaging suite 10 illustrated in FIG. 4 may include one or morefeedback sensors 232 configured to monitor a position, velocity,acceleration, or a combination thereof, of the ram 190, as indicated byarrow 234. In turn, the one or more sensors 232 may provide a feedbacksignal 236 to a control 238, which may provide a closed loop controlsignal 240 to the fluid pumps 182. Similar to the embodiments describedabove, the illustrated injector 12 may be substantially or entirely freefrom ferrous materials, magnetic materials, or a combination thereof. Inaddition, the illustrated injector 12 may be substantially or entirelyfree of electronics or other components that may potentially emit RFradiation, magnetic fields, or other potential interference with the MRIsystem. Again, the illustrated control 238, the fluid pumps 182, and anyferrous or magnetic materials may be disposed on an opposite side of thewall 48 relative to the fluid driven injector 12.

FIG. 5 is a diagram of a partial view of the fluid drive 160 coupled tothe gear and ratchet assembly 162 of the embodiment of FIG. 4. Asillustrated, the opposite reciprocating flows 186 and 188 through theconduits 176 and 178 to/from the first and second chambers 170 and 172cause the piston 164 and the rod 168 to reciprocate inwardly andoutwardly as indicated by arrow 250. In response to this reciprocatingmovement 250, the rod 168 causes the third arm 204 to rotate in areciprocating manner about the bearing 210 as illustrated by arrow 216.In turn, the reciprocating rotation 216 of the third arm 204 causes thefirst and second arms 200 and 202 to reciprocate forward and backwardrelative to the gear 194 as indicated by arrows 252 and 254. Forexample, as the first arm 200 moves forward toward the gear 194, thesecond arm 202 moves away from the gear 194. The reverse is also true.As the second arm 202 moves toward the gear 194, the first arm 200 movesaway from the gear 194. During these reciprocating movements, one of thefirst and second arms 200 and 202 pushes against one of the teeth 218 onthe gear 194, as the other one of the arms withdraws and falls into asubsequent tooth 218 on the gear 194. Thus, the first and second arms200 and 202 alternate between a forward motion pushing against the teeth218 to drive the gear 194 and a reverse motion stepping into asubsequent tooth 218, thereby creating a sequence of forces to rotatethe gear 194 in a stepwise manner. Again, the sequence of forces may bedefined as a series of separate and discrete forces, which are generatedand/or occur one after another rather than a single constant force. Inthe present embodiment, the sequence of forces may progressively forcethe gear 194 to rotate by engaging one tooth 218 after another indiscrete steps, e.g., contact a first tooth 218, push it forward, stepto a second tooth 218, push it forward, and so on. Each force in thesequence may be equal or different. Also, each force in the sequence maybe separated in time and/or spatial position. Again, the components ofthe fluid drive 160 and the gear and ratchet assembly 162 may besubstantially or entirely free of ferrous materials, magnetic materials,and components that may emit or be adversely affected by RF radiation,magnetics, and so forth.

FIG. 6 is a diagram of an alternative embodiment of the imaging suite10, wherein the injector 12 includes an injector powerhead 260configured to mate with a docking recharge station 262. The illustratedpowerhead 260 may include a pneumatic recharge port 264, a pneumaticactuator port 266, a pneumatic supply 268, a pneumatic switch/valve 270,a fluid drive 272, one or more feedback sensors 274, and a medical fluiddelivery device 276. The station 262 may include a retractor 278, one ormore controls 280, a pneumatic supply 282, a pneumatic recharge port284, and a pneumatic actuator port 286. The injector 12 may include anexternal pneumatic source 288 configured to supply a pneumatic workingmedium to the port 264, the port 284, or a combination thereof, via oneor more removable conduits 290. Thus, the source 288 may replenish thepneumatic supplies 268 and 282 via the ports 264 and 284. The ports 284and 286 may be coupled to the supply 282 via conduits 292 and 294. Theconduits 292 and 294 may include one or more valves, such as checkvalves 296 and 298, to control the pneumatic flow. The pneumatic supply282 may include one or more valves to control the pneumatic flow to andfrom the ports 284 and 286. For example, the illustrated supply 282 mayinclude a valve 300 configured to open and close the pneumatic flowthrough the conduit 294 and the port 286. For example, the valve 300 maybe controlled by the one or more controls 280. The controls 280 mayinclude a valve actuator, a flow meter, or a combination thereof.

The powerhead 260 may be configured to operate separate from orconnected with the station 262. For example, the port 286 may removablycouple with the port 266 via a pneumatic conduit 302. The conduit 302may supply the pneumatic working medium from the supply 282 to the fluiddrive 272 via the valve 270. However, in the illustrated embodiment, thefluid drive 272 receives the pneumatic working medium from the localpneumatic supply 268, while the valve 270 opens and closes in responseto pneumatic pressure supplied through the port 266. In other words, thevalve 270 is actuated by a pneumatic pressure provided by the station262, while the actual pneumatic working medium is stored locally withinthe supply 268. Thus, the port 266 provides a pneumatic control pressureto the valve 270 via a conduit 304. Upon opening the valve 270 inresponse to pneumatic control pressure, the pneumatic working medium inthe supply 268 flows through conduits 306 and 308 to the fluid drive272. In turn, the fluid drive 272 responds to the pneumatic pressurefrom the supply 268 to impart a driving force 310 on the delivery device276. During operation of the powerhead 260, one or more feedback sensors274 may monitor conditions 312 and 314 of the fluid drive 272 and thedelivery device 276, and provide feedback signals 316 to the control(s)280 in the station 262.

After the powerhead 260 completes an injection of medical fluid, thepneumatic supply 268 may be recharged by the source 288. The pneumaticmedium may pass through the port 264, through a conduit 318, and intothe supply 268. In addition, the retractor 278 disposed on the station262 may be used to retract the position of the fluid drive 272 for asubsequent injection. For example, the retractor 278 may include amanual or powered retractor, which can retract a ram into apre-injection position. The illustrated imaging suite 10 of FIG. 6 mayinclude a control 320 disposed on an opposite side of the wall 48relative to the injector 12. Again, the powerhead 260 and the station262 may be substantially or entirely free of ferrous materials, magneticmaterials, and electronics that potentially generate or become adverselyaffected by RF radiation, magnetics, and so forth. However, in someembodiments, the control(s) 280 and/or the valve 300 may includeelectronics that generally do not operate during an imaging procedure ofthe MRI system.

FIG. 7 is a diagram of an embodiment of the powerhead 260 and station262 of FIG. 6, further illustrating structural characteristics of thesecomponents 260 and 262. In the illustrated embodiment, the powerhead 260may include a plurality of patient body mounts, such as arm/leg straps330. These straps 330 may be coupled together via buttons, clips,hook-and-loop material, buckles, and/or other appropriate manners ofcoupling. The powerhead 260 may be described as a patient mountableinjector (e.g., removably mounted), which is particularly well suitedfor placement with the patient inside the imaging bore 14 as discussedabove with reference to FIG. 1. One of the benefits of a patientmountable injector is that less tubing may be required for an injectionthan with a conventional injector that is mounted on a stand, wall, orceiling. The illustrated powerhead 260 includes a flow adjuster 332 anda syringe adjuster 334. Furthermore, the powerhead 260 includes asyringe receptacle 336 configured to support a syringe 338. As discussedabove with reference to FIG. 6, the fluid drive 272 disposed within thepowerhead 260 is responsive to a pneumatic pressure to drive a plunger340 of the syringe 338. The fluid drive 272 may be triggered by apneumatic pulse or pressure supply from the station 262 through aconduit 302 to the powerhead 260. Moreover, the control 280 disposed onthe station 262 may be used to control various aspects of the powerhead260. The station 262 may include flow valve adjusters or adjustmentconnections 342 and 344. Finally, the illustrated retractor 278 may be amanual retractor mechanism, which can be inserted into the syringereceptacle 336 to force a ram of the fluid drive 272 back into apre-injection position. Alternatively, the retractor 278 may have apressure or motor-assisted mechanism to force the ram of the powerhead260 back into a pre-injection position. The illustrated station 262 maybe coupled to a main control 346 and user interface 348 of the control320 via electrical cables 350 and 352. However, the main control 346 anduser interface 348 may be configured to not operate during an injectionprocedure with the powerhead 260. Therefore, the powerhead 260 andstation 262 would do not interfere with operation of the MRI system.

FIG. 8 is a diagram of an exemplary embodiment of the powerhead 260 ofFIGS. 6 and 7, further illustrating a multi-fluid configuration of thefluid drive 272 similar to the embodiment described above with referenceto FIG. 2. In the illustrated embodiment, the fluid drive 272 includes apneumatic drive section 360 coupled to a liquid drive section 362.Specifically, the sections 360 and 362 may be divided by a piston 364disposed movably (e.g., capable of sliding back and forth, or in areciprocating fashion) within a cylinder 366. The liquid drive section362 may include a conduit 368 leading to a reservoir 370, wherein aplurality of valves 372 and 374 are disposed between the reservoir 370and the piston 36410 control flow of a liquid 376 toward the reservoir370 during movement of the piston 364. The conduit 368 also may includea pump 378 configured to force the fluid to flow between the liquiddrive section 362 and the reservoir 370, as discussed further below. Thepiston 364 may be coupled to a ram 380, which is configured to drive theplunger 340 into the syringe 338.

In the embodiment of FIG. 8, the pneumatic working medium disposedwithin the supply 268 may provide pressure to move the piston 364 uponopening the valve 270 in response to the pneumatic control pressureprovided through the port 266. Thus, the pneumatic working medium forcesthe piston 364 to move the ram 380 against the plunger 340, while theliquid 376 within the liquid drive section 362 provides accurate controlof the movement of the piston 364 via the valves 372 and 374. Forexample, the valves 372 and 374 may be adjusted or set by the station262, thereby controlling the flow rate of the liquid 376 to thereservoir 370. In this manner, the liquid pressure within the section362 at least partially opposes the pneumatic pressure in the pneumaticdrive section 360, thereby slowing down the movement of the piston 364to provide a controlled injection with the syringe 338. Upon completingan injection, the pump 378 may be engaged by the station 262, such thatthe liquid pressure overcomes the air pressure to return the piston 364to a pre-injection state. In the illustrated embodiment of FIG. 8, thefluid drive 272 is substantially or entirely non-ferrous, non-magnetic,and without electronics.

FIG. 9 is a diagram of an alternative embodiment of the fluid drive 272of FIGS. 6-8, illustrating a dual-syringe configuration driven by amulti-fluid drive assembly. Specifically, the fluid drive 272 of FIG. 9may include a first piston 390 disposed moveably along a first cylinder392, such that a first ram 394 can move a first plunger 396 in a firstsyringe 398. The fluid drive 272 includes a second piston 400 disposedmoveably within a second cylinder 402, such that a second ram 404 canmove a second plunger 406 in a second syringe 408. The first piston 390divides the first cylinder 392 into a first pneumatic chamber 410 and afirst liquid chamber 412. Similarly, the second piston 400 divides thesecond cylinder 402 into a second pneumatic chamber 414 and a secondliquid chamber 416. The first and second pneumatic chambers 410 and 414may be separated from one another or in fluid communication with oneanother. For example, in the illustrated embodiment, the chambers 410and 414 are part of a common pneumatic chamber 418. In some embodiments,the chamber 418 is open to atmosphere, whereas other embodiments of thechamber 418 are under a suitable pressure to provide a driving forceagainst the first and second pistons 390 and 400.

The fluid drive 272 includes a liquid reservoir 420 in fluidcommunication with the first and second liquid chambers 412 and 416. Theillustrated reservoir 420 may be coupled to the first and secondchambers 412 and 416 via one or more liquid conduits 422, 424, 426, 428,and 430, which may include various valves, pumps, or a combinationthereof. For example, the illustrated conduits 422 and 424 may include apiezoelectric selector valve 432 to control liquid flow from the chamber412, or the chamber 416, or both, to the liquid reservoir 420 viasubsequent conduits. The conduit 426 may include a piezoelectric servovalve 434 configured to provide speed control of the liquid flow betweenthe chambers 412 and 416 and the reservoir 420. The conduit 428 mayinclude a check valve 436 and a gear pump 438 to provide liquid from thereservoir 420 back to the chamber 412, the chamber 416, or both. Thus,the check valve 436 may restrict flow from the chambers 412 and 416toward the reservoir 420, while permitting the reverse flow from thereservoir 420 to the chambers 412 and 416.

The fluid drive 272 may include first and second position sensors 440and 442 configured to sense the position of the first and second pistons390 and 400, respectively. Thus, the position sensed by the sensors 440and 442 may be used to control the movement of the first and secondpistons 390 and 400 via the piezoelectric servo valve 434. In otherembodiments, the valves 432 and 434 may be replaced with other suitablevalve assemblies, such as pneumatically controlled valves, opticallycontrolled valves, and so forth.

Again, the pneumatic pressure within the chamber 418 generally drivesthe pistons 390 and 400. The liquid pressure within the chambers 412 and416 generally regulates the movement of the pistons 390 and 400, therebyproviding accurate motion control of the plungers 396 and 406 into therespective syringes 398 and 408. Moreover, the illustrated fluid drive272 may be substantially or entirely free of ferrous materials, magneticmaterials, or a combination thereof. Thus, the injector 12 isparticularly well suited for operation with the MRI system, and isrelatively compact and patient mountable for placement within theimaging bore 14 as discussed above with reference to FIG. 1.

FIG. 10 is a diagram of an alternative embodiment of the imaging suite10 of FIG. 6, wherein the powerhead 260 and the station 262 areconfigured with fiber optics in combination with pneumatic controls.Specifically, the powerhead 260 may include a multimedia port 450, apneumatic valve 452, an optical/light switch 454, a fluid drive 456, amedical fluid delivery device 458, and one or more feedback sensors 460.The station 262 may include a retractor 462, one or more controls 464, apneumatic supply 466, an optical/light source 468, a recharge port 470,and a multimedia port 472. In addition, the injector 12 includes amultimedia conduit 474 removably coupled to the ports 450 and 472.

In the illustrated embodiment, the multimedia conduit 474 is configuredto transmit both a pneumatic working medium and an optical/light signalbetween the ports 450 and 472. Specifically, the port 472 may receivethe pneumatic working medium from the supply 466 via a conduit 476 and asignal from the source 468 via a conduit 478. These transmissions may beinitiated by the control(s) 464 and/or user interaction with a control480. Thus, the pneumatic working medium and the optical/light signal maybe simultaneously transmitted through the conduit 474 as indicated byarrows 482 and 484. Upon receipt at the port 450, the pneumatic workingmedium may be transmitted to the valve 452 via a conduit 486, while theoptical/light signal may be transmitted to the switch 454 via a conduit488.

In turn, the switch 454 generally controls operation of the valve 452.For example, the signal 484 may trigger the switch 454 to open or closethe valve 452, thereby controlling flow of the pneumatic working medium482 toward the fluid drive 456 via conduit 490. The pneumatic pressuresupplied to the fluid drive 456 then creates a driving force or pressure492, which drives a medical fluid from the medical fluid delivery device458 and into the patient. During operation, the sensor(s) 460 maymonitor conditions 494 and 496 of the fluid drive 456 and the deliverydevice 458, and provide feedback signal(s) 498 to the control(s) 464.Similar to the embodiment of FIG. 6, the recharge port 470 may receivean additional supply of the pneumatic working medium from an externalpneumatic source 500 through a conduit 502. Advantageously, themultimedia conduit 474 enables transmission of different types of mediato provide both power and control functions simultaneously between thestation 262 and the powerhead 260.

While the invention may be susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, it should be understood that the invention is not intended tobe limited to the particular forms disclosed. Rather, the invention isto cap all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the followingappended claims.

The invention claimed is:
 1. A medical system, comprising: a magnetic resonance imaging system comprising an imaging bore; a fluid-driven injector disposed within the imaging bore and comprising a fluid delivery device, a fluid conduit, a working fluid, and a substantially non-ferrous and substantially non-magnetic fluid drive, wherein the fluid drive is configured to not interfere with magnetic resonance imaging; at least one pump; a flowpath extending between the at least one pump and the fluid drive; a working fluid, wherein the at least one pump provides the working fluid to the fluid drive through the flowpath; and a wall with shielding, wherein the at least one pump and the fluid-driven injector are disposed on opposite sides of the wall; wherein the fluid drive is responsive to pressure of the working fluid from the at least one pump to impart a sequence of forces to drive the delivery device to flow medical fluid from the injector, wherein the fluid drive is configured to sequentially squeeze the fluid conduit, wherein the fluid drive comprises a plurality of pistons disposed in series along the fluid conduit, and wherein the pistons are configured to move sequentially to impart the sequence of forces at different times and axial positions along the fluid conduit.
 2. The medical system of claim 1, wherein the fluid drive is configured to not emit or detect radio frequency radiation.
 3. The medical system of claim 1, further comprising a control coupled to the at least one pump.
 4. The medical system of claim 1, wherein the delivery device has an output disposed generally proximate the fluid drive.
 5. The medical system of claim 1, wherein the fluid drive further comprises a separate cylinder for each piston, and wherein the medical system further comprises: a working fluid source coupled to the fluid drive, wherein the working fluid source comprises the working fluid, the at least one pump, and a manifold; and a separate working fluid conduit extending between each of the cylinders of the fluid drive and the manifold, wherein the working fluid source provides sequential pulses one after another to the cylinders of the fluid drive to cause movement of the corresponding pistons, and wherein the flowpath comprises each working fluid conduit.
 6. The medical system of claim 5, wherein the at least one pump is on an inlet side of the manifold and the working fluid conduits are on an outlet side of the manifold.
 7. The medical system of claim 5, wherein the at least one pump is a single pump, and wherein the working fluid source comprises a plurality of valves corresponding to the number of cylinders and corresponding pistons.
 8. The medical system of claim 5, wherein the at least one pump comprises multiple pumps, and wherein the working fluid source comprises a plurality of valves corresponding to the number of cylinders and corresponding pistons. 